Respiratory System II - Neck-Larynx PDF

RESRIRATOR Y TRACT II October 21-25th, 2024 Professor Dr Panagiotis Karanis Professor and Director of Anatomy Institute Coordinator Unit of Anatomy and Morphology Coordinator of the Unit Infectious Diseases and One Health UNic M...

RESRIRATOR Y TRACT II October 21-25th, 2024 Professor Dr Panagiotis Karanis Professor and Director of Anatomy Institute Coordinator Unit of Anatomy and Morphology Coordinator of the Unit Infectious Diseases and One Health UNic Medical School The LOBs of this lecture Describe the anatomy of the larynx (including vertebral levels) and its roles in digestion and voice production. Recognise the importance of dividing the neck into triangles. Describe the anterior and posterior triangles and their major subdivisions (submental, muscular, carotid, suboccipital and subclavian triangles). Describe the major groups of neck muscles. Recognise the anatomical landmarks for the insertion of a central venous line. Describe and identify the origins, course and relations of the major arteries and veins in the neck. Identify major neurovascular structures on medical images of the head and neck. Describe the fascial layers of the neck (investing, pretracheal and prevertebral, and the carotid sheath). Identify the intrinsic and extrinsic muscles of the larynx, and their functions. Describe the innervation of omohyoid and digastric muscles and of the extrinsic and intrinsic muscles of the larynx. Identify the roots and trunks of the brachial plexus in the posterior triangle. Identify normal mediastinal anatomy on sectional CT / MRI and anatomical sections. Introduction The anatomy of the head and neck is very complicated secondary to the numerous fine structures that have a variable course and depth as they traverse through the tissue. There are several very important neurovascular structures anatomically situated in the head and neck , which may suffer a potential injury during surgical dissection. Neck fascial layers  Platysma muscle Platysma. The thin platysma muscle spreads subcutaneously like a sheet, passes over the clavicles, and is pierced by cutaneous nerves. The platysma (G. flat plate) is supplied by branches of the facial nerve, CN VII. Carotid sheath Triangles To allow clear communication regarding the location of structures, injuries, or pathologies, the neck is divided into regions. Function of the Neck Triangles The anterior and posterior triangles of the neck provide a natural framework to organize the numerous contents of the neck into well-defined anatomic subdivisions. The muscles, bones, and fascia of the cervical region form natural boundaries that enclose various other structures, including muscles, nerves, vasculature, and lymphatics. The following sections will further define the anterior and posterior triangles, clarify the contents of each, and discuss their clinical and surgical relevance.  Cervical regions and triangles Between the cranium (mandible anteriorly and occipital bone posteriorly) and clavicles, the neck is divided into four major regions based on the usually visible and/or palpable borders of the large and relatively superficial SCM and trapezius muscles, which are contained within the outermost (investing) layer of deep cervical fascia.  Anterior triangles Submandibular (digastric) Posterior triangles Submental Occipital Carotid Omoclavicular (subclavian) Muscular (omotracheal) Carotid triangle of the neck Anatomic Boundaries / Anterior Triangle The anterior triangles refer to bilateral anatomic subdivisions of the neck comprising the anterior surface of the neck , deep to the superficial cervical fascia and platysma muscle. Laterally, the anterior triangle is bounded by the anterior border of the sternocleidomastoid muscle. Its superior border is the inferior border of the mandible. Medially, the boundary is the midline of the neck. The anterior triangle can further subdivide into four sub-triangles. The submandibular and submental triangles are the superior divisions, while the muscular and carotid triangles compose the inferior divisions of this anterior neck compartment. The submandibular triangle is delineated by the inferior border of the mandible and the anterior and posterior bellies of the digastric muscle. The submental triangle is demarcated by the hyoid bone, the anterior belly of the digastric muscle, and the midline of the neck. The muscular triangle is outlined by the anterior aspect of the sternocleidomastoid and superior belly of the omohyoid, the midline of the neck , and the hyoid bone. The outline of the carotid triangle is the anterior aspect of the sternocleidomastoid, the superior belly of the omohyoid, and the posterior belly of the digastric and stylohyoid muscles. The investing layer of the deep cervical fascia encases all of the infrahyoid muscles and forms the superficial boundary of the entire anterior triangle. The deep boundary of the carotid and muscular triangles is composed of the pretracheal layer of the deep cervical fascia, while the mylohyoid muscle forms the deep boundary of the submandibular and submental triangles. The submandibular gland, a major salivary gland, emerges from the lateral aspect of the mylohyoid muscle and occupies most of the submandibular triangle. Anatomic Boundaries Posterior Triangle The posterior triangle of the neck is posterior to the anterior triangle. The boundary of this triangle is the posterior surface of the sternocleidomastoid, the anterior surface of the trapezius, and the middle third of the clavicle. The sternocleidomastoid and trapezius muscles join at the superior nuchal line, which forms the apex of the triangle. The investing layer of deep cervical fascia makes up the superficial border of the posterior triangle, while the prevertebral fascia makes up the floor. The inferior belly of the omohyoid muscle passes deep to the sternocleidomastoid and crosses through the posterior triangle, further dividing it into the occipital and subclavian sub-triangles. The posterior neck triangle is a clinically relevant anatomic region that contains many important vascular and neural structures. The clinical aspect of the anatomy contained in the posterior neck triangle is useful for a wide variety of medical specialties, including anesthesiology, otolaryngology, physical medicine and rehabilitation, and others. Posterior triangle of the neck. Olek Remesz (wiki-pl: Orem, commons: Orem) Modified by user:madhero88 - license: https://creativecommons.org/licenses/by/3.0/deed.en Posterior triangle & scalenus anterior Posterior triangle & scalenus anterior Superficial veins on the neck The superficial temporal and maxillary veins merge, forming the retromandibular vein, the posterior division of which unites with the posterior auricular vein to form the EJV. The facial vein receives the anterior division of the retromandibular vein before emptying into the internal jugular vein, deep to the SCM. The anterior jugular veins may lie superficial or deep to the investing layer of the deep cervical fascia. Central line insertio n "Blausen 0181 Catheter CentralVenousAccessDevice NonTunneled" by BruceBlaus. When using this image in external sources it can be cited as:Blausen.com staff. "Blausen gallery 2014". Wikiversity Journal of Medicine. DOI:10.15347/wjm/2014.010. ISSN 20018762. - Own work. Licensed under CC BY 3.0 via Commons - https://commons.wikimedia.org/wiki/File:Blausen_0181_Catheter_CentralVenousAccessDevice_NonTunneled.png#/media/ File:Blausen_0181_Catheter_CentralVenousAccessDevice_NonTunneled.png  Anterior cervical region – Extrinsic muscles of the larynx Anterolateral part of the neck The hyoid provides attachments for the suprahyoid muscles superior to it and the infrahyoid muscles inferior to it. These hyoid muscles steady or move the hyoid and larynx. Suprahyoid group muscles: mylohyoid, geniohyoid, stylohyoid, and digastric. Digastric has: 2 bellies, posterior and anterior / intermediate tendon / fibrous sling derived from the pretracheal layer. Infrahyoid group muscles: Sternohyoid, omohyoid, sternohyoid, thyrohyoid Omohyoid has: 2 bellies, superior and inferior / intermediate tendon/fascial sling connects to the clavicle. Anterior Region Thyroid Gland Consists of 2 lobes joined by an isthmus. Occasionally there is a pyramidal lobe as well. Thyroid - Clinical The risk of injury to the recurrent laryngeal nerves is ever present during neck surgery. Hoarseness is the usual sign of unilateral recurrent nerve injury; however, temporary aphonia or disturbance of phonation (voice production) and laryngeal spasm may occur. These signs usually result from bruising the recurrent laryngeal nerves during surgery or from the pressure of accumulated blood and serous exudate after the operation. A goitre, or goiter, is a swelling in the neck resulting from an enlarged thyroid gland. A goitre can be associated with a thyroid that is not functioning properly.Worldwide, over 90% of goitre cases are caused by iodine deficiency. The term is from the Latin gutturia, meaning throat. Most goitres are of a benign nature. Important Structures Clinical Relevance: Medical Uses of the Carotid Triangle In the carotid triangle, many of the vessels and nerves are relatively superficial, and so can be accessed by surgery. The carotid arteries, internal jugular vein, vagus and hypoglossal nerves are frequent targets of this surgical approach. The carotid triangle also contains the carotid sinus – a dilated portion of the common carotid and internal carotid arteries (see next slide). It contains specific sensory cells, called baroreceptors. The baroreceptors detect stretch as a measure of blood pressure. The glossopharyngeal nerve feeds this information to the brain, and this is used to regulate blood pressure. Carotid sinus: a dilation of the proximal part of the internal carotid artery, which may involve the common carotid artery. Innervated principally by the glossopharyngeal nerve (CN IX) through the carotid sinus nerve as well as by the vagus nerve (CN X), it is a baroreceptor (pressoreceptor) that reacts to changes in arterial blood pressure. Carotid body: a small, reddish brown ovoid mass of tissue in life that lies in a septum on the medial (deep) side of the bifurcation of the common carotid artery in close relation to the carotid sinus. Supplied mainly by the carotid sinus nerve (CN IX) and by CN X, it is a chemoreceptor that monitors the level of oxygen in the blood. It is stimulated by low levels of oxygen and initiates a reflex that increases the rate and depth of respiration, cardiac rate, and blood pressure. In some people, the baroreceptors are hypersensitive to stretch. In these patients, external pressure on the carotid sinus can cause slowing of the heart rate and a decrease in blood pressure. The brain becomes underperfused, and syncope results. In such patients, checking the pulse at the carotid triangle is not advised.  Cervical Plexus of Nerves Consists of a superficial cervical plexus and a deep cervical plexus. - There are 5 main components of the cervical plexus: 1) Cutaneous branches (supplying lesser occipital, greater auricular, transverse cervical, and supraclavicular nerves) 2) Ansa cervicalis (which innervates the infrahyoid and geniohyoid muscles). 3) Phrenic nerve -What muscle does this innervate? 4) Contributions to the accessory nerve (CN XI). - What muscles are innervated by this nerve? 5) Direct muscular branches (which supply the prevertebral muscles of the neck). *Clinical Correlations: Cervical Plexus Block - The cervical plexus block provides anaesthesia and analgesia to the head and neck region. - Depending on the type of surgery, the plexus can be blocked either at superficial or deep levels. - Superficial branches of the plexus innervate the skin and superficial structures of the head, neck , and shoulder. - The deep branches innervate the muscles of the deep anterior neck and the diaphragm. - The superficial cervical plexus block is used for superficial cutaneous surgeries of the head and neck. A deep cervical plexus block is used for deeper surgeries of the neck , such as carotid artery or thyroid surgery.  Erb‘s Point The cervical plexus is a nerve plexus of the anterior rami of the first (i.e. upper-most) four cervical spinal nerves C1-C4. The cervical plexus provides motor innervation to some muscles of the neck, and the diaphragm; it provides sensory innervation to parts of the head, neck, and chest. Wilhelm Heinrich Erb (30 November 1840 – 29 October 1921) was a German neurologist. He was born in Winnweiler, What is the Ansa cervicalis ? The ansa cervicalis is a neural loop in the neck formed by connecting the superior root from the cervical spinal nerves (C1–2) and the inferior root descending from C2–C3. It has various anatomical variations and can be an important acknowledgment in specific operations of the neck region.  C1 (travel with Innervation XII hypoglossal) Facial nerve V - mandibular Inferior alveolar Ansa cervicalis C1 – C3 Ansa cervicalis C2 – C3  The upper airways The neck is between the face and trunk. The front part is of gristle and through it speech and respiration take place; it is known as the windpipe. Aristotle, Historia animalium, 4th century BC. The #gristle# (cartilage) that Aristotle describes is important in preventig the collapse of the uppper airways, which in turn is vital to lung function because although the gas exchange of respiration takes place deep withing the lungs, those parts of the respiratory system outside the chest, which are reffered to as the upper airways, allow and effect the process, and are of such clinical importance that they must be considered (the structures of the upper airways are clearly seen in the next slide). Larynx Neck MRI 1. Nasal cavity 2. Nasopharynx 3. Pharynx 4. Larynx 5. Tongue 6. Spinal column 7. Spinal cord 8. Epiglottis 9. Cricoid cartilage Hyoid, larynx and trachea Why the name ‚hyoid‘ ? (L. Os hyoideum)  The trachea It transports air to and from the lungs. It is about 12 cm long and 2.5 cm in diameter; lies in front of the oesophagus The posterior gaps in the tracheal rings are spanned by the tracheal muscle. It ends at the level of the sternal angle or the T4-T5 IV disc. It divides into right and left primary bronchi at the spinal level of T5. It is made of cartilage “rings” that are c-shaped (open of c at the back). The tracheal cartilages keep the trachea patent. Smooth muscle - the trachealis muscle - bridges the gap at the back. The trachea divides at the carina into the primary bronchi. Tracheal epithelium Tracheal epithelium propels debris-laden mucus toward the pharynx for expulsion from the mouth. Acknowledgment to: anatomybox.com, biosciences.org, funscrape.com, studyblue.com The larynx  The larynx The skeleton of the larynx is made of pieces of cartilage that articulate with each other. The most important are: thyroid cricoid arytenoid The epiglottis is a leaf-shaped cartilage that lies behind the tongue. The epiglottis moves down during swallowing to protect the airway. The inlet of the larynx is the upper opening. Voice is produced by movement of the vocal cords when they come into contact. There are muscles that move the vocal cords. Larynx  Skeleton of Larynx Views of an isolated arytenoid cartilage Arytenoid cartilage 1, cartilago curniculata 2, apex 4, vocal process (projects anteriorly, provides attachment to the vocal ligament) 5, muscular process projects laterally, for attachment of posterior and lateral crico-arytenoid muscles. Inferior of the larynx Muscles and nerves of Larynx and crico-thyroid joint VARIATIONS IN SHAPE OF RIMA GLOTTIDIS  Cricothyroid Transverse INTRINSIC MUSCLES OF LARYNX Posterior Tenses arytenoid crico-arytenoid Superior laryngeal nerve Adduct all Abdduct cords (All else recurrent laryngeal) The actions of the intrinsic laryngeal muscles are easiest to understand when they are considered as functional groups: adductors and abductors, sphincters, and tensors and relaxers Lateral Thyro-arytenoid crico-arytenoid whisp Oblique arytenoid Relaxes Adduct all Adduct cords only Vessels, nerves, and lymph nodes of the larynx Laryngeal branches of the right nerve (CN X)  CLINICAL PICTURES CT / MRIs DEFINITION / EXPLANATION OF TERMS Conio-tomy (Crico-thyro-tomy) Thacheo-tomy Tracheo-stomy Laryng-ectomy Laryngo-scopy CT and MRI of Thyroid Tumor Note trachea displaced from the midline  Note the following: Thyroid Cartilage Arytenoid Cartilages Vertebral Body Epiglottis High Resolution T1-Weighted MRI of the Larynx  Anterior Neck Lipoma Mimicking a Goiter JV = Jugular vein C = Carotid artery THY = Thyroid T = Trachea Aspiration of Foreign Bodies Neck MRI 1. Nasal cavity 2. Nasopharynx 3. Pharynx 4. Larynx 5. Tongue 6. Spinal column 7. Spinal cord 8. Epiglottis 9. Cricoid cartilage Indirect laryngoscopy Endotracheal Intubation  Take Home Message Surgery is applied anatomy; anatomical knowledge is a basic requirement for a less complication, damage- free surgery. Anatomy is a prerequisite for good quality patient care.  Summary 34. Describe the anatomy of the larynx (including vertebral levels) and its roles in digestion and voice production. 35. Recognise the importance of dividing the neck into triangles. Describe the anterior and posterior triangles and their major subdivisions (submental, muscular, carotid, suboccipital and subclavian triangles). 36. Describe the major groups of neck muscles. 37. Recognise the anatomical landmarks for the insertion of a central venous line. 38. Describe and identify the origins, course and relations of the major arteries and veins in the neck. 39. Identify major neurovascular structures on medical images of the head and neck. 40. Describe the fascial layers of the neck (investing, pretracheal and prevertebral, and the carotid sheath). 41. Identify the intrinsic and extrinsic muscles of the larynx, and their functions. 42. Describe the innervation of omohyoid and digastric muscles and of the extrinsic and intrinsic muscles of the larynx.  The illustrations and slides for this presentation were taken from:  Netter, Atlas of human anatomy  Snell, clinical anatomy for medical students  Tortora & Grabowski, principles of anatomy and physiology  Wikipedia  TeachMe Anatomy  Taschenatlas Anatomie. 2 Innere Organe. H. Fritsch-W. Kühnel. 9.Auflage. Thieme  Review: Anatomy, Head and Neck , Posterior Cervical Region. James Stathakios, Michael A. Carron.In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan.2020 Jul 31. PMID: 31855365.NBK551521.  Review. Anatomy, Head and Neck , Posterior Neck Triangle. Jarett Casale , Zachary Geiger. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan. 2020 Aug 15. PMID: 30725974. NBK537289.  Review. Anatomy, Head and Neck , Anterior Cervical Region. Aaisha Shah, Bruno Cunha. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan. 2020 Jul 31. PMID: 32491407.NBK557475.  Moore, Dalley, Agur, Clinically Oriented Anatomy, 7th Ed.  Moore, Dalley, Agur, Clinically Oriented Anatomy, 8th Ed.